For vice squads, Craigslist personals, home to many a paid hookup, make prostitution busts as easy as buying a couch. So why is an Illinois lawman suing the website?

Cook County Sheriff Thomas Dart is suing Craigslist. He says it's "the single largest source of prostitution in the nation," and he's scheduled a press conference to discuss the move.

Why sue Craigslist? The site rolls over when the police come calling, and the data it gives up about its users regularly results in large-scale arrests for prostitution. In 2007, Dart's department arrested 254 people in a four-month-long bust. A similar bust in New York's Westchester County yielded 66 arrests. Police in Irvine, Calif. and Everett, Wa.directly credited Craigslist ads with helping them make arrests.

Why shut down such a rich vein? It's telling that Dart is making a big, public stink about prostitution on Craigslist. If his goal were stopping prostitution, he'd want to keep Craigslist open, providing his department with a steady source of leads. It's easier than staking out street corners.

No, Dart needs to be seen as stopping prostitution. And that requires calling out Craigslist. He'd better hope he doesn't succeed, because pushing the whores and johns to darker corners of the Internet will mean he and his men will have to work a lot harder to keep their arrest numbers up.

(Photo via KOMO)